This career development award supports the growth of Dr. Susmita Pati into an independent health services researcher focusing on health care access for medically underserved children and families. Dr. Pati brings to this award her prior experience as a pediatrician with particular expertise in underserved populations and fellowship training in epidemiology. Dr. Pati's career development will be guided by a multidisciplinary team of nationally recognized research mentors including Donald F. Schwarz, MD MPH (longitudinal cohort studies, career development, health policy), Daniel Polsky, PhD (research development, methodology, health care access), Trevor Hadley, PhD (mental health services research, health policy), and Avital Cnaan, PhD (advanced statistical methods). Her program will consist of formal didactics and practical experience gained through conduct of original research, complemented by intensive mentorship. The proposed projects will allow her to utilize and further develop her skills in population-based primary research (i.e. study design, sampling and survey techniques, advanced statistical analysis) to examine predictors of stable health care access among medically underserved populations. The mentoring relationships, advanced formal training and education, and protected time afforded by this career development award will raise the sophistication, rigor and quality of her work and significantly facilitate her transition to a highly successful, independent, patient-oriented clinical investigator. Dr. Pati's research plan primarily examines associations between child, maternal, policy-level factors and stability of Medicaid coverage at the national and local level through two linked studies. In the first study, she investigates national trends (1997-2001) in various dimensions of health care access (insurance status, coverage gaps, access barriers) by low-income children and families, both welfare-recipients and non-recipients, using nationally representative datasets. In the second study, she conducts a longitudinal cohort study of medically underserved children from Philadelphia to identify child, maternal, and policy predictors of discontinuous Medicaid coverage and she begins to examine links between unstable coverage and child health care utilization and child health. The analyses from the first study will anchor the results from the second study in a national context and guide variable definition in the subsequent analysis. The cohort study is closely tied to her educational goals to gain practical experience in the design, conduct, and analysis of population-based cohort studies involving primary data collection. In the future, these projects will lead to examination of the relationship between unstable Medicaid coverage, child health care utilization, and, ultimately, child health and developmental outcomes.